<!DOCTYPE html>
<html lang="en">
<head>
    <!--类型转化string转number number转String-->
    <meta charset="UTF-8">
    <title>javaScript toString</title>
</head>
<script>
    var x = 12;
    var y = true;
    document.write(x.toString());
    document.write(typeof x.toString() );

    var z = "123.0";
    document.write(parseInt(z));
    document.write(typeof parseInt(z));

</script>
<body>

</body>
</html>